[R] symbolic manipulations
jdm at xnet.com
Sat Apr 7 01:51:13 CEST 2001
I copied code from an Splus manual to take symbolic derivatives:
my.deriv <- function( mathfunc, var )
tmp <- substitute(mathfunc)
name <- deparse(substitute(var))
(The code also works in R).
When I try this on x^2 I get
> my.deriv(x^2, x)
2 * x
Suppose I assign the output of my.deriv(x^2, x) to deriv.xsqr :
> deriv.xsqr <- my.deriv(x^2, x)
2 * x
My question is, how do I take the derivative of deriv.xsqr
(I want the answer to be 2) ?
The naive guess
> my.deriv(deriv.xsqr, x)
is obviously wrong.
I suspect that, to get the derivative I'm looking for, I need to
something like deparse(deriv.xsqr) into my.deriv, but this doesn't
Thanks in advance,
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